In the growing of mushrooms the mushroom compost is generally placed in a mushroom bed. A digger is moved longitudinally down the bed from one end of the bed to the other. The digger has tines which dig into the compost so that, for example, spawn and supplement can mixed into the compost. A compactor which is usually in the form of a pair of rollers then moves over the compost to compact and level the surface of the compost. Where such digger and compacting units are combined the resultant assembly could be quite heavy weighing, for example, over 300 pounds. This makes it difficult to move the assembly from one bed to another.